Gov. Chris Christie is someone else who just made it onto this stage and needs to find a way to break through and get attention. Typically, one would do that by going after the candidates at the head of the pack — Donald J. Trump or Jeb Bush.

Mr. Christie decided to go after Rand Paul, attacking him for his opposition to national antiterrorism surveillance policies. On one hand, that allows the New Jersey governor to invoke the Sept. 11, 2001, attacks and the threat of terrorism and portray Mr. Paul as being out of the Republican mainstream on these issues.

But Mr. Christie sure walked into it as Mr. Paul tied him to President Obama on this issue — quickly invoking Mr. Christie’s hug with the president during the final weeks of the 2012 presidential campaign, when Mr. Obama went to New Jersey in the midst of Hurricane Sandy.